1. Field of the Invention
The invention relates to a connecting rod for an internal combustion engine and to an internal combustion engine.
2. Description of the Related Art
DE 10 2010 016 037 A1 and FIG. 1 herein show a connecting rod of an internal combustion engine having an adjustable compression ratio. The connecting rod 10 has a big end bearing eye 11 and a small end bearing eye 12. The big end bearing eye 11 is used to attach the connecting rod 10 to a crankshaft (not shown in FIG. 1) and the small end bearing eye 12 is used to attach the connecting rod 10 to a cylinder piston (not shown in FIG. 1) of the internal combustion engine. The connecting rod 10 is assigned an eccentric adjusting device 13 that has an eccentric (not shown in FIG. 1), an eccentric lever 14 and eccentric rods 15, 16. The eccentric lever 14 has an aperture arranged eccentrically with respect to a center 17 of the small end bearing eye 12 and the aperture has a center 18. The aperture in the eccentric lever 14 accommodates the eccentric and an aperture in the eccentric accommodates a piston pin. The eccentric adjusting device 13 is used to adjust an effective connecting rod length leff, which refers to the distance of the center 18 of the aperture in the eccentric lever 14 from a center 19 of the big end bearing eye 11. The eccentric rods 15, 16 can be moved to turn the eccentric body 14 and hence to change the effective connecting rod length leff,. Each eccentric rod 15, 16 is assigned a piston 20, 21 that is guided movably in a hydraulic chamber 22, 23. A hydraulic pressure prevails in the hydraulic chambers 22, 23 and acts on the pistons 20, 21 assigned to the eccentric rods 15, 16. The movement of the eccentric rods 15, 16 is possible or not possible, depending on the oil quantity in the hydraulic chambers.
The adjustment of the eccentric adjusting device 13 is initiated by inertia forces and load forces of the internal combustion engine that act on the eccentric adjusting device 13 during an operating cycle of the internal combustion engine. The directions of the forces acting on the eccentric adjusting device 13 change continuously during an operating cycle. The adjusting movement is assisted by the pistons 20, 21 acted upon by hydraulic oil. The pistons 20, 21 act on the eccentric rods 15, 16 and prevent return of the eccentric adjusting device 13 due to varying directions of action of the forces acting on the eccentric adjusting device 13. The eccentric rods 15, 16 that interact with the pistons 20, 21 are attached to the eccentric body 14 on both sides. The hydraulic chambers 22 and 23 in which the pistons 20, 21 are guided can be supplied with hydraulic oil from the big end bearing eye 11 via hydraulic oil lines 24 and 25. Check valves 26 and 27 prevent the hydraulic oil from flowing back out of the hydraulic chambers 23 and 24 into the hydraulic lines 24 and 25. A changeover valve 29 is accommodated in a bore 28 in the connecting rod 10. The switching position of the changeover valve 29 determines which of the hydraulic chambers 22 and 23 is filled with hydraulic oil and which is emptied, wherein the adjusting direction or turning direction of the eccentric adjusting device 13 depends thereon. In this case, the hydraulic chambers 22 and 23 are in contact via fluid lines 30 and 31, respectively, with the bore 28 that accommodates the changeover valve 29. An actuating means 32, a spring device 33 and a control piston 34 of the changeover valve 29 are shown schematically in FIG. 1. The operation of these components of the changeover valve 29 is known from DE 10 2010 016 037 A1.
As explained above, the hydraulic oil that acts on the pistons 20, 21 is fed to the hydraulic chambers 22, 23 via hydraulic lines 24 and 25, starting from the big end bearing eye 11. Thus, the connecting rod 10 engages on the crankshaft (not shown in FIG. 1) by means of the big end bearing eye 11 so that a connecting rod bearing shell 35 is between a crankshaft bearing journal of the crankshaft and the big end bearing eye.
It is the object of the invention to provide an improved internal combustion engine and an improved connecting rod.